The present invention relates to apparatus and method for controlling the supply of fuel of the cylinders of a multi-cylinder internal combustion engine by successively inactivating the combustion of one or more of the cylinders in response to sensed engine operating parameter.
It is known in the art to reduce the number of active or ignited cylinders in which combustion takes place when the depression in the intake manifold increases in terms of vacuum in order to reduce fuel consumption under light load conditions. However, under the light load conditions the increased depression in the intake manifold results in a deficient supply of air or a mixture of air and fuel to the reduced number of ignited cylinders and less power is available than is required to supply enough power. This is particularly disadvantageous when the engine is idled since the loss of power would case instability of the engine revolution and the driver has to depress the accelerator pedal to supply additional air or air-fuel mixture to the engine in order to compensate for the loss of power even when the vehicle is at rest. Therefore, it has been difficult to reduce the number of ignited cylinders under the idling conditions without the loss of power to thereby achieve fuel economy.